Reflex Movement Flashcards
What are the three principle types of movements we can initiate?
Involuntary actions- reflexes
semi- automatic actions
voluntary actions
What are involuntary actions?
No conscious element- involuntary
centred on spinal cord (spinal nerves) and brain stem (crainial nerves)
stereotyped response
monosynaptic circuit
What is the duration of a reflex like?
rapid- short latency (can have delay)
For motor pathways what is the common final pathway?
Motor neurons-to affected organ
where can motor neuron cell bodies be found?
spinal cord (somatic)
Brainstem (crainial nerves)
How are motor neurons activated?
by various brain regions (cortex)
various peripheral receptors (reflex)
The grey matter in a spinal cord can be devided into what?
(the H shape across the middle)
dorsal horn
intermediate horn
ventral horn
where do motor neurons leave the spinal cord?
The vental horn of grey matter
Describe the strech reflex pathway
stimuli goes along peripheral nerve hits sensory afferent enters in the dorsal horn of spinal cord passes through to motor neurons in ventral horn which leaves at spinal level bringing about a strech
what is a key point for initiating a reflex response?
activation of receptor endings that are mechanoreceptors and these are essentially the muscle spindles found within belly of muscle
what are muscle spindles conposed of?
Intrafusal fibres
wrapped around by sensory nerve endings- mechanoreceptors
these fuse together to give rise to Group 1a afferent (Aalpha axon)
When the muscle is streched from it’s relaxed state what is extended within muscle spindles?
intrafusal fibres- causes ap
What is a summary of the stretch reflex pathway
Stimulus– activates receptor (mechanoreceptor— transduction of stimulus into an AP– conducted along group 1a sensory axon— reach spinal cord results in synaptic transmission on recruitment of motor neuron, motor neuron can conduct along motor axon aalpha—- results in synaptic transmission release of acetylcholine to respond with muscle contraction
give experiments you can use to find the physological features of stress?
jaw jerk reflex- clench teeth on mandible, ankle jerk reflex- tap on achiles tendon
Is there a difference in the latency or amplitude between jaw and ankle jerk reflexes?
latency for jaw jerk reflex is less than that for ankle because neural pathway for the jaw jerk reflex is shorter than that of the ankle
aplitude for jaw jerk reflex is less than that for ankle because masseter is smaller muscle
